POS0285 TEMPOROMANDIBULAR JOINT INVOLVEMENT IN JUVENILE IDIOPATHIC ARTHRITIS: THE ROLE OF MAGNETIC RESONANCE IMAGING IN THE EVALUATION OF THE SILENT JOINT
Authors: C. Brusadelli, D. Mariano, A. Pistorio, L. Anfigeno, F. Magnaguagno, M. Valle, M. DI Filippo, G. Chiappe, N. Laffi, C. Malattia
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Temporomandibular joint (TMJ) involvement is frequent in patients with Juvenile Idiopathic Arthritis (JIA) and may cause severe craniofacial growth disturbances. Contrast-enhanced MRI is considered the best available tool for TMJ assessment<sup>[1]</sup>. <h3>Objectives</h3> To investigate the agreement between MRI and physical examination in the detection of TMJ involvement; to describe the evolution of TMJ activity and osteochondral damage by means of MRI during disease course; to evaluate the relationship between socio-demographic, clinical variables and radiologic outcomes in terms of resolution of inflammation and structural damage progression. <h3>Methods</h3> 121 JIA patients with TMJ involvement who underwent at least 2 MRI examinations in our Centre between 2012 and 2022 were included in this retrospective study. TMJ inflammation and damage were evaluated according to the MRI scoring system proposed by the OMERACT (<i>Outcome Measures in Rheumatology and Clinical Trials</i>)<sup>[2]</sup>. The agreement between physical examination and MRI was analysed by means of Cohen's kappa coefficient. The relationship between socio-demographic and clinical variables and radiologic outcomes was estimated by bivariate analyses. Comparison between survival curves for damage progression was done by the Log-Rank test. <h3>Results</h3> 339 TMJ MRIs obtained from 121 JIA patients were reviewed. First MRI was performed at a median time of 0.6 years (0.2-1.5) after TMJ symptoms onset. Baseline MRI showed active synovitis in 85 out of 121 patients (70.2%) and condylar damage in 112 (92.6%) patients. A poor agreement was found between physical examination and MRI (right TMJ Cohen's kappa = 0.15; left TMJ Cohen's kappa = 0.26). MRI showed active TMJ synovitis in 63% of the exams performed in patients who were in clinical remission according to Wallace criteria. During follow-up, synovitis improved in 56.2% of patients and structural damage progression was observed in 21.0% of patients. Younger age (&lt; 9.4 years) at onset of TMJ involvement was associated with the resolution of the inflammatory process (p=0.023) and with a lower rate of structural damage progression (p=0.027). Significant association was observed between persistence of TMJ synovial inflammation and damage progression (p=0.0013). Higher baseline MRI synovitis (p=0.018) and bone erosion scores (p&lt;0.0001) were associated with the development of a severe osteochondral damage at last follow-up MRI. <h3>Conclusion</h3> Our study confirms that TMJ involvement is clinically silent in most of JIA patients and supports the role of MRI in the diagnosis and monitoring of TMJ arthritis. Active TMJ synovitis was found in a substantial proportion of patients in clinical remission with relevant implications for the therapeutic strategy. Old age at TMJ onset, a high degree of synovial inflammation and its persistence over time were negative prognostic factors for the development of severe TMJ damage. <h3>References</h3> [1]Arabshahi B, Cron RQ. Temporomandibular joint arthritis in juvenile idiopathic arthritis: the forgotten joint. Curr Opin Rheumatol. 2006 Sep;18(5):490–5; [2]Tolend MA, Twilt M, Cron RQ, Tzaribachev N, Guleria S, von Kalle T, et al. Toward Establishing a Standardized Magnetic Resonance Imaging Scoring System for Temporomandibular Joints in Juvenile Idiopathic Arthritis. Arthritis Care Res (Hoboken). 2018 May;70(5):758–67. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None declared.